1. Field of the Art
This invention relates to an endoscopic insertion instrument which is suitable for use in medical examinations, and more particularly to an endoscopic insertion instrument having a wire guide mechanism incorporated into a flexible body portion of the insertion instrument for guiding operating wires which are pulled back and forth at the time of flexibly bending an angle section of the instrument.
2. Prior Art
As for endoscopes of medical use, for example, it has been known to employ an insertion instrument of the construction as shown in FIG. 5. In that figure, indicated at 1 is a manipulating head, at 2 an elongated insertion instrument and at 3 a universal cable. A major part of the elongated insertion instrument 2 is constituted by a flexible body section 2a which is connected to the manipulating head 1 at its proximal end. An angle section 2b is connected to the fore end of the flexible body section 2a, and further a rigid tip end section 2c is connected to the fore end of the angle section 2b. Illumination means as well as image pickup means are mounted on or in the rigid tip end section 2c. The angle section 2b is flexibly bendable to turn the rigid tip end section 2c into desired directions. The flexible body section 2a is also arranged to be arbitrarily bendable along a path of insertion at the time of introduction into a body cavity.
Illustrated in FIG. 6 is a joint portion which connects the angle section 2b with the flexible body section 2a of the insertion instrument. Incorporated into the flexible body 2a, which is required to be bendable in arbitrary directions, is a flexible coil shaft 10 which is formed by helically winding narrow metal strips. Generally, the coil shaft 10 is of a double-coil tube construction consisting of two coil windings of opposite directions. The coil tube 10 is enshrouded in a mesh layer 11 which is in turn enshrouded in a flexible outer skin layer 12.
On the other hand, the angle section 2b is flexibly bent into an angular form by remote control from an angle knob 4 which is provided on the manipulating head 1 of the endoscopic insertion instrument. In construction, the angle section 2b is constituted by a series of angle rings 13 which are pivotally connected one after another by means of vertically and transversely aligned pivoting pins 14. Namely, preceding and succeeding angle rings 13 which are pivotally connected with each other by means of a pair of pivoting pins 14 are pivotally flexible relative to each other in a direction perpendicular to an axis of the paired pivoting pins 14. Further, the angle rings 13 are connected successively and alternately by vertically aligned pivoting pins and transversely aligned pivoting pins, so that the angle section 2b can be turned arbitrarily in upward and downward directions as well as rightward and leftward directions. Similarly to the elongated flexible body 2a, the angle rings 13 of the angle section 2b are wrapped in successively by a mesh layer 15 and a flexible outer skin layer 16.
As described above, the flexible body 2a and angle section 26 of the endoscopic insertion instrument distinctively differ from each other in construction. Therefore, it is after the flexible body 2a and the angle section 2b are assembled separately that a proximal end portion of the angle section 2b is connected to a fore end portion of the flexible body 2a of the insertion instrument. For the purpose of connecting the flexible body 2a and the angle section 2b with each other, connecting rings 17 and 18 are provided on the flexible body 2a and the angle section 2b, respectively. Namely, a connecting ring 17 is securely fixed, for example, by welding to the fore end of the coil tube 10 of the flexible body 2a. On the other hand or on the side of the angle section 2b, a connecting ring 18 which constitutes a rearmost angle ring of the angle section 2b is pivotally connected to an adjacent angle ring 13 by pivoting pins 14. Alternatively, the connecting ring 18 can be securely fixed to a rearmost angle ring by welding if desired.
The angle section 2b is connected to the flexible body 2a of the insertion instrument by partly fitting the connecting ring 18 into the connecting ring 17 on the side of the flexible body 2a. The connecting ring 17 on the side of the flexible body 2a, which is located on the outer side of the connecting ring 18, is provided with an aperture or apertures 19. Solder 20 is filled into the apertures 19 to fix the two connecting rings 17 and 18 to each other in a securely connected state. The outer skin layer 12 of the flexible body 2a is butted against the outer skin layer 16 of the angle section 2b. A line wrapping is formed across the butted ends of the outer skin layers 12 and 16, and an adhesive is applied on the line wrapping. Thus, the angle section 2b is connected to the flexible body 2a almost seamlessly.
In this instance, fitted in the insertion instrument 2 are various component parts, including a light guide consisting of a bundle of fiber optics for transmission of illumination light, a signal cable in the case of an electronic endoscope (an image guide consisting of a bundle of fiber optics in the case of an optical endoscope), a biopsy channel, an air/water feed channel etc. Operating wires are 21 also fitted in the insertion instrument 2 in order to flexibly bend the angle section 2b by remote control. A couple of operating wires are threaded in upper and lower positions in the insertion instrument 2 in case the angle section 2a is to be angularly bent in upward and downward directions, and four operating wires are threaded in upper, lower, right and left positions in the angle section 2b is to be bent in rightward and leftward directions as well as upward and downward directions. Fore ends of the operating wires 14 are fixedly anchored on a foremost angle ring of the angle section 2b or on the rigid tip end section 2c. Further, within the angle section 2b, the operating wires 21 are successively passed or threaded through the pivoting pins 14 or lancing arches which are formed in the angle rings 13. On the other hand, within the flexible body 2a, the operating wires 21 are passed through sheathing guide coils 22, which are each in the form of a tightly wound coil of a metallic wire with adjacent helices tightly closed to each other. The fore end of each closed sheathing coil 22 is securely fixed at a joint portion of the flexible body 2b with the angle section 2b, while the operating wires 21 are led out through the fixed end portion of the respective closed sheathing coils 22 and further extended forward through the angle section 2b. 
Illustrated in FIG. 7 is the construction at and around the fixed fore ends of the closed sheathing coil 22 which serve as guide means for the operating wires 21. Anchor pins 23 are fixedly planted by caulking, for example, on the inner one of the two connecting rings 17 and 18, that is, on the connecting ring 18 on the side of the angle section 2b. Head portions 23a of the anchor pins 23 are located on the inner side of the connecting ring 18 and are each provided with a wire guide hole 24, in which an anchor pipe 25 is fixedly fitted by brazing or by other suitable means for fixing a fore end portion of a closed sheathing coil 22. The anchor pipe 25 is in the form of a stepped pipe having a large diameter portion 25a and a small diameter portion 25b. A fore end portion of each closed sheathing coil 22 is fixedly anchored in the large diameter portion 25a, for example, by brazing. An operating wire 21 alone is threaded through the smaller diameter portion 25b which is fitted in the guide hole 24 of the anchor pin 23, while the large diameter portion 25a is extended toward the flexible body 2a. 
In assembling the insertion instrument 2, it is necessary to fix the two connecting rings 17 and 18 between the flexible body 2a and the angle section 2b firmly to each other. For this purpose, a flux is filled in the apertures 19 in the connecting ring 17 on the side of the flexible body 2a before applying solder to the apertures 19, thereby to distribute the solder all over the joining surfaces of the two connecting rings 17 and 18. By so doing, the connecting rings 17 and 18 can be fixed to each other securely over broader surface areas. Use of a large amount of flux may result in exudation of extra flux through gaps between the two connecting rings 17 and 18. Exudation of flux from end portions of the outer connecting ring 17 on the side of the flexible body 2a would not give rise to any serious problem in particular as long as it is relatively small in amount. However, flux which exudes from end portions of the inner connecting ring 18 on the side of the angle section 2b, if any, will get into internal portions of the insertion instrument 2, particularly into internal portions of the flexible body.
The operating wires 21 are passed internally of the end position of the connecting ring 18 on the side of the angle section 2b, along with the closed sheathing coils 22 in which the operating wires 21 are threaded. Each operating wire 21 is constituted by a large number of stranded fine metal filaments, and slid within the closed sheathing coil 22 at the time of flexibly bending the angle section 2b. The above-mentioned flux, which has migrated into internal portions of the insertion instrument 2 from end portions of the connecting ring 18 on the side of the angle section 2b, can get into the closed sheathing coils 22 and stick on the surface of the operating wires 21 to cause oxidation of the constituent fine metal wires of the operating wires 21. Under such circumstances, due to corrosive deteriorations, the operating wires 21 are subjected to abrasive wear in a conspicuously increased degree while in sliding contact with the closed sheathing coils 22 and are caused to break in a worst case.
With the foregoing situations in view, it is an object of the present invention to provide a joint construction for connecting an angle section to an elongated flexible body of an endoscopic insertion instrument, which permits to solder the angle section and the flexible body firmly and securely together by the use of a flux in such a way as to preclude possibilities of flux deposition on operating wires of the angle section.
It is another object of the present invention to provide a joint construction for connecting an angle section to an elongated flexible body of an endoscopic insertion instrument, which can ensure smooth movements of angle section operating wires within closed sheathing coils even if a relatively large amount of flux is applied to increase soldering surface areas of connecting rings.
It is still another object of the present invention to provide a joint construction for connecting an angle section to an elongated flexible body of an endoscopic insertion instrument, which can improve durability of angle section operating wires.
In order to achieve the above-stated objectives, according to the present invention, there is provided a joint construction for an endoscopic insertion instrument which is basically composed of a rigid tip end section with an observation window and an illumination window, an elongated flexible body, and an angle section connected between said rigid tip end section and said flexible body. More particularly, according to the present invention, there is provided a joint construction for connecting an angle section to a fore end of a flexible body of an endoscopic insertion instrument, which comprises: a couple of connecting rings opposingly provided at joining ends of the angle section and the flexible body for fitting engagement with each other, one on the outer side of the other one; an aperture or a plural number of apertures provided in an outer one of the connecting rings to supply solder to overlapped joining surfaces of the connecting rings at the time of fixedly soldering the connecting rings to each other; at least one operating wire threaded and extended through the angle section and the elongated flexible body of the insertion instrument via the connecting rings for flexibly bending the angle section; a closed sheathing coil coextensively provided in the flexible body for encasing the operating wire and having a fore end portion thereof securely fixed to an inner one of the connecting rings; and a fluid-tight shield portion formed on and around outer periphery of the closed sheathing coil over a predetermined range in axial length, including at least proximal end portions of the inner connecting ring, to prevent a flux from intruding into the closed sheathing coil at the time of soldering the connecting rings together.
In this instance, the closed sheathing coil can be fixed to one of the connecting rings either directly or through an anchor pipe. For example, the anchor pipe can be constituted by a large diameter portion which is to receive a fore end portion of the closed sheathing coil, and a small diameter portion which is fixedly stopped in an inner one of the connecting rings by an anchor pin and internally provided with an axial wire passage for threading therethrough an operating wire coming out of the closed sheathing coil. In a case where the anchor pipe is arranged in the way just described, the shield portion is formed to cover the outer periphery of the closed sheathing coil over a predetermined range in axial length from the large diameter portion of the anchor pipe. In this case, it is the connecting ring on the side of the angle section to which the closed sheathing coil is connected either directly or through an anchor pipe.
In a case where the closed sheathing coil is fixed by the use of an anchor pipe, the shield portion is formed on and around the closed sheathing coil in such a way that it is connected to the anchor pipe at one end and extended into the flexible body of the insertion instrument at the other end thereof. Preferably, the other end of the shield portion is axially extended beyond the connecting ring on the side of the flexible body and into a helical coil structure which forms a bone structure of the flexible body. Further, preferably the shield portion is constituted by a soft and resilient structure although this is not a mandatory requisite. In one preferred form of the invention, the shield portion is formed by applying a soft and resilient seal material on and around the outer periphery of a closed sheathing coil portion on the proximal side of the anchor pipe. Alternatively, the shield portion can be formed by fitting a flexible tube on the outer periphery of the closed sheathing tube.
The above and other objects, features and advantages of the present invention will become apparent from the following particular description of the invention, taken in conjunction with the accompanying drawings which show by way of example some preferred embodiments of the invention. Needless to say, the present invention should not be construed as being limited to particular exemplary forms shown.